Lithofacies types and influence on bitumen saturation in x-horizon of the Nigerian tar sand deposits.
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Date
2016
Authors
Akinmosin, A
Imo, D
Journal Title
Journal ISSN
Volume Title
Publisher
Ife Journal of Science
Abstract
Bitumen saturation, particle size distribution and mineralogical analyses were carried out on some tar sand
deposits in parts of southwestern Nigeria with a view to determining their sedimentological properties and the
degree of bitumen saturation of the respective lithofacies. Fifty one fresh samples collected at 1 m intervals from
13 different locations were prepared for further studies by soaking in toluene, to extract the bitumen from the
reservoir sands and subsequently subjected to granulometric analysis. The sands were air-dried and dry-sieved to
establish the grain size classes for the different locations. The dry samples were further analyzed petrographically
to deduce the textural characteristics and transportation history. Moreover, heavy mineral analysis was carried
out to determine the sediments' maturity and their provenance. From the textural study, five different lithofacies
were established namely: very fine sand, fine sand, medium sand, coarse sand and very coarse sand. Results
showed that the samples from some locations were well sorted, while others ranged from poorly sorted to well
sorted with average standard deviation range of 0.32 – 1.28Φ. The average graphic mean of 1.24Φ and average
standard deviation value of 0.91Φ revealed that majority of the sands were medium grained. Most of the
sediments were leptokurtic while others were mesokurtic to platykurtic. The skewness of all the samples varied
from very fine skewed to very coarse skewed. The grain shape ranged from angular to well rounded. The heavy
mineral analysis result showed that the sediments were mostly mineralogically immature except for those from
Idiobilayo, Loda and Trianga. The average percentage bitumen impregnation for Imeri (coarse sand) was 15.5%;
Okerisa (medium sand) was 25%; while that of Tirianga (fine sand) was 30.60%. The results generally showed
that fine-grained facies had higher tar saturation than the medium and coarser grained sizes, which suggested
that bitumen saturation in the study area was influenced by particle size.
Description
Keywords
Bitumen , Tar Sand , Provenance , Maturity , Sorting , Lithofacies.
Citation
Akinmosin, A., & Imo, D. (2016). Lithofacies types and influence on bitumen saturation in x-horizon of the Nigerian tar sand deposits. Ife Journal of Science, 18(1), 103-118.